Cinnamyl phenols

The other axis of this property/property plot is the C/V lignin ratio (Fig. 15.15b), which is the weight ratio of total cinnamyl phenols to total vanillyl phenols. This tracer is based on the general relationship that cinnamyl phenols are obtained from the CuO oxidation of nonwoody plant tissues, whereas vanillyl phenols are produced by all vascular plant tissues, including woods. Phytoplankton do not produce either cinnamyl or vanillyl phenols, and hence have no effect on C/V ratios. Woods produce only trace amounts of cinnamyl... 

Vanillyl phenols Syringyl phenols Cinnamyl phenols p-Hydroxyl phenols Sum of phenols ( Lig/g organic carbon) % phenol carbon totd organic carbon ... 

High-temperature cupric oxide (CuO) oxidation of vascular plant lignins yields the eight simple phenols illustrated here as major reaction products. These reaction products comprise monomethoxylated (vanillyl) and dimethoxylated (syringyl) phenols, which occur primarily as aldehydes, along with smaller amounts of the corresponding ketones and acids. Two cinnamyl phenols (p-coumaric and ferulic acid) are also produced that retain the three-carbon side chain of the original structural units and terminate in a carboxyl. 

Cyclodehydrogenation (2, 115-116). Cardillo et al.s have extended their work on cyclodehydrogenation with this reagent to conversion of o-cinnamyl phenols into A3-flavenes. The starting materials are prepared by reaction of cinnamyl... 

Unusual cyclocarbonylation of allylic acetates proceeds in the presence of acetic anhydride and an amine to afford acetates of phenol derivatives. The cinnamyl acetate derivative 408 undergoes carbonylation and Friedel-Crafts-type cyclization to form the a-naphthyl acetate 410 under severe condi-tions[263,264]. The reaction proceeds at 140-170 under 50-70 atm of CO in the presence of acetic anhydride and Et N. Addition of acetic anhydride is essential for the cyclization. The key step seems to be the Friedel-Crafts-type cyclization of an acylpalladium complex as shown by 409. When MeOH is added instead of acetic anhydride, /3,7-unsaturated esters such as 388 are... 

Aryl alcohol oxidase from the ligninolytic fungus Pleurotus eryngii had a strong preference for benzylic and allylic alcohols, showing activity on phenyl-substituted benzyl, cinnamyl, naphthyl and 2,4-hexadien-l-ol [103,104]. Another aryl alcohol oxidase, vanillyl alcohol oxidase (VAO) from the ascomycete Penicillium simplicissimum catalyzed the oxidation of vanillyl alcohol and the demethylation of 4-(methoxymethyl)phenol to vanillin and 4-hydro-xybenzaldehyde. In addition, VAO also catalyzed deamination of vanillyl amine to vanillin, and hydroxylation and dehydrogenation of 4-alkylphenols. For the oxidation of 4-alkylphenol, the ratio between the alcohol and alkene product depended on the length and bulkiness of the alkyl side-chain [105,106]. 4-Ethylphenol and 4-propylphenol, were mainly converted to (R)-l-(4 -hydroxyphenyl) alcohols, whereas medium-chain 4-alkylphenols such as 4-butylphenol were converted to l-(4 -hydroxyphenyl)alkenes. 

The second type of data is derived from biochemical experiments related to the three cinnamyl alcohols—/>-coumaryl alcohol (I), coniferyl alcohol (II), and sinapyl alcohol (III) and their phenolic glucosides— >-glucocoumaryl alcohol (IV), coniferin (V), and syringin (VI). These and the following formulas do not differentiate between cis and trans isomers. 

Thioacidolysis allows the distinction between products derived from lignin and products derived from />coumaric and ferulic acids, and the distinction between products derived from cinnamaldehydes and cinnamyl alcohols. Recent improvements have made it possible to estimate the fraction of free phenolic groups in uncondensed lignin (see Section 1.3.1), and to depolymerize the dimers, so that they can be included in the analysis of the lignin composition. 

Allyl ethers of orf/io-disubstituted phenols rearrange to the corresponding p-allylphenols. It is noteworthy that the para rearrangement is not usually accompanied by inversion of the allyl group.8-4-6-6-7 For example, cinnamyl 2-carbomethoxy-6-methylphenyl ether (III) rearranges without inversion8 to yield the p-cinnamyl derivative (IV). 

The structure of XXVI was deduced from the fact that it was different from the 2-cinnamylphenol obtained by direct C-cinnamylation of phenol.16 Later investigators showed that XXVI is the sole product ozonization yielded formaldehyde but not benzaldehyde. 7-Methyl-allyl phenyl ether also rearranges with inversion, yielding 2-(a-methyl-allyl)-phenol 36 the structure of the rearrangement product has been definitely established87 38 by a combination of degradative and synthetic procedures. 

The extent of C-alkylation as a side reaction in etherification varies about 1% of allyl 2-allylphenyl ether is formed when phenol is used in the acetone and potassium carbonate method with allyl bromide with cinnamyl bromide or 7,7-dimethylallyl bromide the extent of C-alkylar tion is greater.16 A complicated mixture of C- and O-alkylation products results from the treatment of phenol with 4-bromo-2-hexene and 4-chloro-2-hexene. 9 4-Hexenylresordnol has been obtained in about 40% yield from the reaction of l-bromo-2-hexene, resorcinol, and potassium carbonate in boiling acetone.99 An appreciable amount of C-alkylation occurs when 2,6-dimethyIphenol is treated with allyl bromide and sodium ethoxide in ethanol.70 Since, in general, the ampunt of C-alkylation is greatly increased by carrying out the alkylation on the sodium salt of the phenol in benzene,16 this method is unsuitable for the preparar tion of allyl aryl ethers. 

Demethoxyabresoline (67) was obtained as a noncrystalline solid. Spectroscopic investigation revealed the presence of a phenolic OH, a 1-phenyl-quinolizidine system, and a trans-cinnamyl group. The stereochemistry at C-l, C-3, and C-5 was the same as in abresoline. The molecular formula C25H29N05 was established by mass spectrometry. The presence of fragment ions at m/e 259 (M —164) and 258 was characteristic of p-hydroxy-cinnamyl esters of the phenylquinolizidol (63a). The assigned structure 68 was confirmed by basic hydrolysis to 63a and p-hydroxycinnamic acid as well as by catalytic hydrogenation to a known dihydro derivative (52). 

Phenols react with cinnamyl compounds via an intermolecular condensation/cyclization providing a reliable method for the construction of dihydrocoumarins. Montmorillonite K-10 clay can catalyze the condensation/cyclization reaction of phloroglucinol and cinnamoyl chlorides to provide a high-yielding route to dihydrocoumarins (Equation 416) <2001S2247>. 

Figure 9.45 Eleven dominant phenolic monomers, yielded from the oxidation of lignin using the CuO oxidation method these compounds can be separated into four families p-hydroxyl, vanillyl (V), syringyl (S), and cinnamyl (C) phenols. (Modified from Hedges...

Figure 9.48 Lignin-phenol concentrations in (a) water column POC and (b) the syringyl-to-vanillyl (S/V) and cinnamyl-to-vanillyl (C/V) ratios of POC at stations in the Baltic Sea from Lulealven River (Lu) to Baltic proper (Bp)—situated from the head (north) to the mouth (south) of the estuary. Other stations are An = Angermanalven BB = Bothnian Bay BSN = Bothnian Sea north BSS = Bothnian Sea south. (Modified from Bianchi et al., 1997.)...

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